Systems and methods for estimating a position of a heart pump

Abstract

Systems and methods are provided herein for estimating a position of a heart pump system in a patient. The system receives first data indicative of a time-varying motor current during a first time period. The motor current corresponds to an amount of current delivered to a motor, while the heart pump system is operating in the patient. The system receives second data indicative of a time-varying differential pressure during the first time period. The differential pressure is indicative of a position of the heart pump system relative to patient's heart. The system receives third data indicative of time-varying motor current during a second time period, and determines an estimate of differential pressure during the second period of time from the third data and a relationship between the first data and the second data. The estimate is usable to predict the position of the heart pump system in the patient.

We claim: 
     
       1. A heart pump system comprising:
 a pump comprising a pump housing and a rotor, the pump housing having a proximal end and a distal end, and the pump being configured to be operated by a motor; 
 a cannula comprising a proximal end and a distal end, wherein the proximal end of the cannula interfaces with the distal end of the pump housing; 
 an elongate catheter extending proximal of the pump housing; 
 one or more sensors, including a differential pressure sensor; and 
 a controller configured to:
 receive a first data indicative of a time-varying motor current during a first period of time while the heart pump system is operating in a patient, wherein the time-varying motor current corresponds to an amount of current delivered to the motor; 
 receive a second data indicative of a time-varying differential pressure measured by the differential pressure sensor during the first period of time, wherein the time-varying differential pressure corresponds to a difference in pressure between an inner portion of the heart pump system and an outside of the heart pump system and is further indicative of a position of the heart pump system relative to patient's heart; 
 receive a third data indicative of time-varying motor current during a second period of time while the heart pump system is operating in the patient, wherein the second period of time is later than the first period of time; 
 determine that the differential pressure sensor has failed when no data is received from the differential pressure sensor during the second period of time; and 
 determine, in response to determining that the differential pressure sensor has failed, an estimate of time-varying differential pressure during the second period of time from the third data and a relationship between the first data and the second data, 
 wherein the estimate of time-varying differential pressure during the second period of time is usable to predict the position of the heart pump system in the patient. 
 
 
     
     
       2. The heart pump system of  claim 1 , wherein the pump is configured to be placed such that the cannula extends across an aortic valve of the patient, the distal end of the cannula being located within a left ventricle of the patient, and the proximal end of the cannula being located within an aorta of the patient. 
     
     
       3. The heart pump system of  claim 1 , further comprising a flexible projection extending distally away from the distal end of the cannula. 
     
     
       4. The heart pump system of  claim 1 , wherein the elongate catheter is coupled on its distal end to the pump housing, and wherein the pump further comprises a drive cable extending through the elongate catheter. 
     
     
       5. The heart pump system of  claim 1 , wherein the controller is further configured to:
 provide a first indicator that the differential pressure sensor has failed; and 
 provide a second indicator that the estimate of time-varying differential pressure during the second period of time is simulated. 
 
     
     
       6. The heart pump system of  claim 1 , wherein the controller is further configured to determine the time-varying differential pressure is drifting by:
 comparing the time-varying differential pressure to the estimate of time-varying differential pressure for the second period of time; 
 calculating, based on comparing the time-varying differential pressure to the estimate of time-varying differential pressure, a difference between the time-varying differential pressure and the estimate of time-varying differential pressure over the second period of time; 
 comparing the difference to a differential pressure signal threshold; and 
 determining, based on comparing the difference to the differential pressure signal threshold, the difference is greater than the differential pressure signal threshold.